First, I'd like to see the ability to highlight a result and assign it to a 'spam' or 'junk' category (preferably with a right-click).

Second, I'd like to see some online help or better explanations of the filtering system: for example, it isn't real clear how to implement the inverse of some of the filter conditions (i.e. DON'T show files less than the value entered as the minimum).

Third, I've come across situations where several files of different sizes have the same name; being able to download all of them automatically with an appended "copy number" (foo(1).bar, foo(2).bar, etc.) would be nice :-)

Finally, when I close one search, it would be nice if the next one on the list were automagically selected.

None of these is anything that would stop me from using Plex; they're just things that would make using it easier/nicer.